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TPS759: new requirement, 1). 5v input, 4~4.6v output. peak 6.5A 2). -2.7v input, -1.2v output, peak 4.1A

Frank Xiao
Genius 12055 points
Part Number: TPS759
Other Parts Discussed in Thread: TPS7A45, TPS7A33

Hi team,

My customer has two new requirement, 

1. 5v input, 4~4.6v output. peak 6.5A

2. -2.7v input, -1.2v output, peak 4.1A

The normal work load very light. the peak current is very high. The waveform is like below,

i know the output cap will supply the current.

Do you have some suggestions and suitable devices about the requirement?

Thanks.

  • 0
    TI__Genius 10490 points
    Hi,

    Please excuse a delay in providing an answer due to the holidays.

    Thanks,
    Gerard
  • 0
    TI__Genius 10490 points
    Hi,

    1. The TPS7A45 is an adjustable device with a fast transient response that can support up to 1.5 A load current, 5 V input, and 4.6 V output.

    2. The TPS7A33 is a negative output low noise LDO that supports up to 1 A load current, -2.7 V input, and -1.2 V output.

    Due to the large but quick load spikes, it is difficult to predict the transient response from these devices. The best way to determine stability is to prototype the design, apply the load, and monitor the output voltage as you have done above.

    Another thing to keep in mind is that the capacitor will draw a large amount of current to recover from the droop in output voltage during a load spike. Similar to startup, recharging the output capacitor can force the LDO into current limit. Constantly operating any LDO in current limit, as seems to be the case in your application, will degrade both performance and longevity.

    Thanks,
    Gerard